Spinnaker sail



March 13, 1951 v, w 2,544,770

SPINNAKER SAIL Filed Jan. 15, 1948 38 Eon 4,90 [/flua. BY 4 MALI-411i) 7, 7%

A HERA 5Y3 Patented Mar. 13, 1951 um'reo STATES PATENT e sence;

SPINNAKERZ SAID; EdwardlV.Mlillis Port-Washingtn,-=N.Y.

Application Januai'y 15, 1948;- Seria-PN'OL- 2,3"'2

5 Claims (Curie-103) This invention relates to a spinnaker orebalfloon sail.

Anobject of the invention isf toiprovide' antinuproved spinnaker sail adapted to take? advantage of the-upward thrust of the wind'z andit'hus tend to lift t'he boat out of the:water:thereb.ydecreas ing 'skin'iriction of the waten' on=the boat;

Another object oi the invention: is. to provide a spinnaken sail with le'ss tendency t'o'oscillate and therefore: easien t'o oontrol and to:- make sleepif Another object of the invention istos provide an improved-spinnaker"sail having a -high degree of'fullness in its upper portion.

Another: object of theinv-ention is to': provide a spinnaker sail: having anincreasedi amount of cloth which isnOt-taXabIeY Another obj ect of the invention is to provide a spinnaker sail having straight lateral edges: or

' leeches.

Another 'object of the invention" is' to provide animproved spinnaker-sail comprising two per:- tions of equal'width each *being' shap'ed on the-to edge so that the outer edge" is longer than the inner edge by a distance 1 e'qua'l to the width of each-'- sail portion:

Another object of the invention is 1 to provide a spinnaker sail' which is simple and inexpensi-ve to make and eflicient in useboth =going, befbre the wind andon a'close' reach:

Other 'objeets'= of the invention will be iir part obvious or-"i'n* part '-pointed out liereinaftent The invention accordingly consists=in therfa tures ofconstruction; combinations of elements, arrangements of parts, and in the several steps and relation" and order 'ofea'clr of" said steps to:

oneror tmore: of the others thereof all: as will" be pointed out in the following deseri-ptionrand the scope of theeapplicationottwhicmwillbe indicated in the followingclaims;

The invention will best*' be understo0d' if the I23 Thee outerlateraliedges: l1 and" I5? nespeoe tively -of: each zoftsaid sail portionsiare-zcutstraight; The? inner edgesmftsaid; sail portions; along subtstantially the lowentwo'ethird's; represented by then numerals: l81;:andgiwrespectively; are: also?) cut straight an'dimayr be; sewnatogether by; auline'. o1 stitching fsubstantiallyparallekth thezouter: edges or: IEEChB'SE of: the: assembled? saili. It. is? to: be understood. that's each of: saidlsailf. portions; may 00121131158732 number of strips :which: may be; 1m dined: with: respect-ate; said i edges? l8 and; 20': re"- s-pectivelw At the topathetsail portions? I0 and: [2 are; cut more or less diagonally fromztheirfouterredgesi M and: It" respectively; inwardly to: oints: on; the inner edges" of: said-t sail' portions; respectively which arebelow the; top: of said. edges by a1 dis tances equal to the width of?" saidi saill portions, which I in the embodiment of theiinvention villus;- ti'ate'df herein is substantially onesthird of the length of the sail vportionssalimgttheir outer: edges respectively. Y, Thus in: shaping:- the.- upper: portion: of the sai1s, a:-distanceX; equal; to the distance Y; which li's the width: ofaisaili ortion; may first be measured" on from: the: top: of the: outer edges 1 of said sail portions as indicatedi in Figure*2i Then the dotte'd line-22 perpendicular: to the outer edge of the E sail portion willi'indicate at its point of intersection with theinners'ed'g es of said sail portions; the upper extremities? of the straight' inner edgeportions: |8 an'd' 20 respecttivelyz This point -of intersectiom which is? indic'at'ed herein by' the :letter 'F; also indicates the '1hwear "ext'remit y ofthe topedge of each sail p'or 'tion: The dotted" line 2 1 represents a diagonal lineextending from' theupperextremity E 01? :the lateral edges of 'said sail" portion to the; point F which ha si beenaestablished as described above. Preferably; however, theupper: edge of the: sail portions" IO an'd I2 respeetively is=not formed by cutting along-this diagonal line 24 Instead itiis prefer-red "to-form a'- curved upper edge extending above"* the diagonal line 2 4 thus providing each sail portion with the roaches ZEi-and 2 8 respectively: Thetop portions of the two sailportions are then-sewed together along,the upper margin of sa'id roaches z t 'and ZB thus' forming a seam 3'0 extending'verti'cally"of the sail; aiong'its mid line from the pealtor'he'adi Pioi" a distanceisubstantially'equal to; the" width". of"'a;s'ai1" portioni I 0"" or 121 Whemtlie sailportionsxlfli anii |2.h"ave1. b'een sewn together along the vertical inner" edges l8 and 20, and along the margins of the upper reaches 26 and 2B, the resulting sail will be substantially oval in shape and. will form a pocket adapted to take advantage of the upward thrust of the wind in an efficient manner thereby tending to lift the boat out of the water and in so doing to decrease the area of surface of the boat in contact with the water. The effect therefore is to decrease the skin friction between the water and the boat and to make the boat go faster.

A spinnaker formed as described above has a larger portion of fullness near the top and the wind striking any portion of the sail is deflected upwardly thus tending to lift the boat as has been stated. The sail thus includes near its top a large amount of cloth which is not taxable.

The term taxable is used herein to mean that the increased amount of cloth which is provided in the sail, due to having the outside edges of the sail parts parallel and not angled inwardly toward the top, will not subject the user to penalty in sailing races. The rules specify the height of a sail for a given class of boat. The increase in width near the top without increasing the height of the sail for a given class of boat thus does not disqualify the boat for racing in its class or subject it to giving handicap.

It is known that wind ordinarily moves along a path which is inclined slightly upward. It has been computed that this upward angle is approximately 4 degrees (Aerodynamics of Sails, by Dr. Manfred Curry, 14, second paragraph). A spinnaker sail formed as described herein is well adapted to take full advantage of this upward thrust of the wind, and to convert even a thrust of the wind parallel to the water into an upward thrust tending to lift the boat.

While the bottom edges 32 and 34 of the sail portions l and I2 respectively may be somewhat curved thus forming a roach at the bottom edge of the sail, the outer lateral edges or leeches l4 and It are made straight as has been described. I have found this desirable since roaches along the leeches or lateral extremities of the sail are impossible to control and tend to flap thereby disturbing the equilibrium of the sail. With the straight edges I have found it much easier to control the sail and make it sleep and thus be more efficient. If desired the edges l4 and I6 may be reinforced by means of a wire 36 embedded in a fold provided by turning back a narrow edge portion of the sail.

Along the lower edges of the sail nips or triangular gathers 38 may be provided at intervals to reduce the width of the sail along its bottom edge and thus aid in promoting the ballooning out of the sail when it is filled with wind, and also contribute to the control of the sail since the shortened length of the bottom edge tends to prevent flapping of the sail along the lower edge.

The sail may be hoisted as indicated in Figure 1 by securing the upper end or peak or head P of the sail to the mast as by a halyard 40 and by securing one lower corner of the sail to the extremity of the boom 42, and securing the other lower corner of the sail to the front of the boat .by the rope 43.

4 parts, all without departing from the scope of the invention, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

What I claim is:

l. A spinnaker sail comprising two parts sewn togetheralong their inner edges, each part having a long outer edge and an inner edge comprising a lower portion parallel to said outer edge, and an upper portion cut substantially diagonally from a point on the said outer edge, which is above the top of the said lower portion of the inner edge by a distance substantially equal to the width of said sail part, along a transverse section taken to the top of said lower portion of the inner edge.

2. The sail as claimed in claim 1 in which roaches are provided along the said upper portions of the inner edges of said sail parts respectively.

3. The sail as claimed in claim 1 in which the upper portions of the inner edges of said sail parts respectively are defined by roaches.

4. A spinnaker sail comprising two parts sewn together along their inner edges each part having a long outer edge and an inner edge comprising a lower portion parallel to said outer edge and an upper portion extending outwardly and upwardly to a point adjoining said outer edge, the said outer edges of said parts being substantially parallel in the assembled sail.

5. A spinnaker sail comprising two parts each having a bottom edge, an outer edge substantially perpendicular to said bottom edge, and an inner edge comprising a lower portion extending substantially at right angles to said lower edge a distance less than the height of the outer edge substantially equivalent to the width of the sail part between said lower portion of the inner edge and the said outer edge, and an upper portion extending from the top of said inner edge lower portion to the top of said outer edge along a curved line having its center in a transverse plane below the lower end of the upper portion of said inner edge and thus defining a roach extending beyond a diagonal line joining the upper end of the lower portion of said inner edge and the top of the said outer edge, said sail parts being sewn together along their inner edges thus providing a sail assembly characterized by the fullness of its top portion.

EDWARD V. WILLIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain 1895 

